The ATM gene, mutated in ataxia telangiectasia (A-T), has been identified by positional cloning. The discovery of ATM may soon allow the identification of A-T heterozygotes, who may be at increased risk of cancer. This study attempted to assess levels of understanding of the genetics of A-T and attitudes toward carrier testing of family members of A-T affected individuals. The sample of A-T parents and siblings was drawn from the A-T Clinical Center at Johns Hopkins, University of California, Los Angeles, and the A-T Children's Project. One hundred and three individuals (68 parents, and 35 adult or adolescent siblings) were interviewed in their homes or over the phone, interviews were taped transcribed verbatim; standard scales of anxiety and depression were administered. Coding scales were developed from qualitative material and inter-rater reliability was obtained. Data analysis has been completed. Results were presented to the A-T Research Group at UCLA in June 1997. Four manuscripts have been prepared, which are being submitted to Nature Genetics, the American Journal of Human Genetics, and the American Journal of Medical Genetics. An abstract was accepted for the ASHG October 1997 meeting in Baltimore. An abstract was invited for submission to the International A-T Workshop in November 1997 in Clermont-Ferrand, France.